From 06eb061f48594aa369f6e852b352410298b317a8 Mon Sep 17 00:00:00 2001 From: Bart Van Assche Date: Fri, 7 Apr 2017 16:50:44 -0700 Subject: dm mpath: requeue after a small delay if blk_get_request() fails If blk_get_request() returns ENODEV then multipath_clone_and_map() causes a request to be requeued immediately. This can cause a kworker thread to spend 100% of the CPU time of a single core in __blk_mq_run_hw_queue() and also can cause device removal to never finish. Avoid this by only requeuing after a delay if blk_get_request() fails. Additionally, reduce the requeue delay. Cc: stable@vger.kernel.org # 4.9+ Signed-off-by: Bart Van Assche Signed-off-by: Mike Snitzer --- drivers/md/dm-mpath.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) (limited to 'drivers/md/dm-mpath.c') diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c index 7f223dbed49f..a4cc4d42117b 100644 --- a/drivers/md/dm-mpath.c +++ b/drivers/md/dm-mpath.c @@ -484,7 +484,6 @@ static int multipath_clone_and_map(struct dm_target *ti, struct request *rq, struct request **__clone) { struct multipath *m = ti->private; - int r = DM_MAPIO_REQUEUE; size_t nr_bytes = blk_rq_bytes(rq); struct pgpath *pgpath; struct block_device *bdev; @@ -503,7 +502,7 @@ static int multipath_clone_and_map(struct dm_target *ti, struct request *rq, } else if (test_bit(MPATHF_QUEUE_IO, &m->flags) || test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags)) { pg_init_all_paths(m); - return r; + return DM_MAPIO_REQUEUE; } memset(mpio, 0, sizeof(*mpio)); @@ -517,7 +516,7 @@ static int multipath_clone_and_map(struct dm_target *ti, struct request *rq, GFP_ATOMIC); if (IS_ERR(clone)) { /* EBUSY, ENODEV or EWOULDBLOCK: requeue */ - return r; + return DM_MAPIO_DELAY_REQUEUE; } clone->bio = clone->biotail = NULL; clone->rq_disk = bdev->bd_disk; -- cgit v1.2.3